The present invention relates to the separation of a mixture of hydrocarbons. In another aspect, this invention relates to the separation of methane and ethane from higher hydrocarbon components such as propane, butane, pentane, and other heavier components present in natural gas. In another aspect, this invention relates to an apparatus useful for de-ethanizing a feedstream wherein said apparatus comprises a de-ethanizer column and a stabilizer. In another aspect, this invention relates to a process for de-ethanizing natural gas liquids wherein the feedstream is put into two streams with one stream being passed directly to the de-ethanizer and the other stream being passed to a stabilizer. In still another aspect, this invention relates to a process for de-ethanizing natural gas liquids wherein a portion of the feedstream is sent to a stabilizer and the overhead vapor obtained from the stabilizer column is passed to the de-ethanizer. In still another aspect, this invention relates to a process of de-ethanizing a natural gas liquids stream wherein a portion of the feedstream is passed to a stabilizer and the feed to the stabilizer and the overhead vapor to the de-ethanizer is cooled by heat exchange means. Another aspect of this invention relates to a process for de-ethanizing natural gas liquids wherein a portion of the feedstream is passed to a stabilizer and the overhead from the stabilizer is passed to the de-ethanizer with the location of introduction of said overhead vapor stream to the de-ethanizer being above the point of introduction of the direct feedstream.
Most natural gas liquids produced are composed of a wide range of hydrocarbons, e.g., "noncondensable" gases such as methane and ethane and "condensable" components such as propane, the butanes and heavier components. It is generally desirable to remove the heavier, condensable components from the methane/ethane components. The separation of the heavier components from the methane/ethane components eliminates problems in the long distance gas transmission of the methane/ethane gases and also allows one to market the heavier components as motor fuel. The cost of building such extraction de-ethanizing facilities can be an exorbitant amount, therefore, it would be understandably desirable to develop a plant which would satisfactorily extract the heavier components from the methane/ethane in an economical manner, e.g., a plant of less expense, smaller size and greater efficiency.
Several frequent problems encountered in a de-ethanizing process are the limitation on the capacity of the de-ethanizer due to the liquid loading in the bottom section of the tower and the greater energy requirements of the de-ethanizer in cooling the overhead vapor to form reflux. A de-ethanizing process which increases the capacity of the de-ethanizer and reduces the refrigeration load on the de-ethanizer as compared to existing processes would, therefore, be desirable in view of the exorbitant cost of building a de-ethanizing plant and the high cost of energy. Especially desirable would be a rather inexpensive and simple change which can be made in existing plants to eliminate such problems as opposed to having to build an entirely new plant in order to increase the capacity and decrease the refrigeration load on the de-ethanizer.
Accordingly, it is an object of this invention to provide an improved de-ethanizing system wherein the limited capacity of the de-ethanizer is increased.
Another object of the present invention is to reduce the refrigeration load on a de-ethanizer.
Still another aspect of this invention is to provide an apparatus set-up which increases the limited capacity of the de-ethanizer and reduces the refrigeration load on the de-ethanizer.
Another object of this invention is to provide an improved separation of relatively low boiling liquids or absorbed gases from a mixture containing these materials and relatively high boiling liquids by a combination of a de-ethanizer and a stabilizer.
Other objects, aspects, and the several advantages of this invention will be apparent to those skilled in the art upon a study of this disclosure, the appended claims, and the drawing.